This is only ideas for opening up different flavours of playstyles.
- Open all weapons for all classes
- All professions have different weapon "stances". So for example a dagger/dagger core ele has it's own unique weapon skills, a dagger/dagger tempest has it's own, and weaver will also have its own unique weapon skills for d/d set. Now the spin here is that you can choose which weapon stance you want to use (depending on expacs you own). So for example, you could be a core d/d ele, but you want to use weaver d/d weapon skills instead of core d/d wep skills and so on. You could be a weaver but with core d/d weapon skills. You get the idea. Or just be a weaver with the weaver d/d weapon skills. This way there is more than one way to play the same set, and could be more fun with different combos or mainhand and offhands depending on what stance you have them. Maybe even core mainhand, and weaver offhand weapon set.
Anet could also open 4th specialisation slot but for pve only.
Of course, I only speak here in terms of making something fun to play with and not with balance in mind because that is a whole different can of worms/pandora's box.